What is units we used for measuring the radon gas?

Bq/m3 (becquerels per cubic meter) or pCi/l (picocuries per litre)

Explanation:

The unit of the International System of Units identified to measure radioactive activity is Becquerelio (Bq) and equivalent to one decay per second.

The Curio (Ci) is also a radioactivity unit, which is still being used in some countries. It owes its name to chemists and chemists Pierre and Marie Curie.

It represents the amount of material in which 3.7 × 1010 atoms per second, or 3.7 × 1010 nuclear decays per second, which is roughly the activity of 1 g of 226Ra (isotope of the chemical chemical element).

The equivalence between the two is:

1Ci= 3,7 × 1010Bq

The specific radioactive activity of a radioactive gas such as radon gas is measured per unit volume and measured in Bq/m3 or pCi/l.

In this case the equivalence is:

1pCi/l= 37Bq/m3